Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
  • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
  • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
  • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
  • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
  • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes
  • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/01—Filters implantable into blood vessels
  • A61F2/0105—Open ended, i.e. legs gathered only at one side
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/01—Filters implantable into blood vessels
  • A61F2002/016—Filters implantable into blood vessels made from wire-like elements
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
  • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
  • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes
  • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
  • A61F2002/91533—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other characterised by the phase between adjacent bands
  • A61F2002/91541—Adjacent bands are arranged out of phase
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
  • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
  • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes
  • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
  • A61F2002/9155—Adjacent bands being connected to each other
  • A61F2002/91558—Adjacent bands being connected to each other connected peak to peak
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0002—Two-dimensional shapes, e.g. cross-sections
  • A61F2230/0028—Shapes in the form of latin or greek characters
  • A61F2230/005—Rosette-shaped, e.g. star-shaped
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0069—Three-dimensional shapes cylindrical
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0073—Quadric-shaped
  • A61F2230/008—Quadric-shaped paraboloidal
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
  • A61F2250/0018—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in elasticity, stiffness or compressibility
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
  • A61F2250/0042—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in shape-memory transition temperatures, e.g. in martensitic transition temperature, in austenitic transition temperature
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
  • A61F2250/0048—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in mechanical expandability, e.g. in mechanical, self- or balloon expandability

Definitions

• the present invention is related to the use of shape memory materials in medical devices.
• a shape memory material can assume an initial high temperature configuration and a deformed low temperature configuration and revert back to the initial high temperature configuration upon the application of heat.
• the high temperature configuration of the material is set into the material or memorized during an initial shaping step in which the material is maintained at a high temperature in a desired shape for a period of time.
• This shape memory exhibited by metals results from the metal undergoing a reversible solid state phase transition. Specifically, the metal transitions from an austenitic state to a martensitic state with a decrease in temperature.
• the temperature at which the transition begins is typically designated M s (martensite start temperature) while the temperature at which the transition finishes is designated M f (martensite finish temperature).
• M s martensite start temperature
• M f martensite finish temperature
• a s Austenitic start temperature
• a f Austenitic finish temperature
• Nitinol stents which are fully expanded in the austenitic state and compressed or partially expanded in the martensitic state have been disclosed.
• the specific Nitinol alloy is chosen such that the stent will be in the austenitic state at body temperature.
• the stent Prior to insertion into the body, the stent is maintained at low temperature corresponding to a temperature within the martensitic range.
• the stent is warmed to at least the A f temperature and in the process expanded to its desired final diameter.
• Shape-memory metals have been disclosed for use in other medical devices as well.
• the present invention is directed to medical devices which use shape- memory materials that have been differentially heat treated to exhibit spatially varying properties such as elasticity and stiffness.
• the present invention is directed to medical devices having been formed, at least in part, from shape-memory materials which have been locally treated to alter their memory characteristics relative to portions of the device which have not been subjected to the local heat treatment. Specifically, a region of the shape-memory material is treated to decrease the stiffness of the region relative to the remainder of the medical device. Desirably, the local treatment will destroy the superelastic properties of the locally treated region.
• the invention is directed in particular to a stent having been formed at least in part of a shape-memory material.
• the stent comprises a plurality of cells arranged in columns extending from one end of the stent to the other. Adjacent columns of cells are interconnected.
• the stent includes at least one differently treated column of cells which has been treated differently from the remainder of the stent to have different shape-memory properties from the remainder of the stent.
• the invention is also directed to a stent wherein at least one of the columns is characterized by a reduced elasticity relative to the remainder of the columns.
• the invention is also directed to a stent wherein at least one of the columns is characterized by a reduced stiffness relative to the remainder of the columns.
• the invention is further directed to a stent wherein at a desired temperature range, at least one longitudinal column of cells does not have superelastic properties while the remainder of the longitudinal columns do have superelastic properties.
• the invention is also directed to a stent having been formed of a shape memory material and comprising a plurality of spaced segments with adjacent spaced segments connected to each other by one or more connector sections.
• Each segment comprises a series of interconnected cells.
• the cells in plan view are of polygonal configuration.
• the segments have a reduced stiffness relative to the connector sections.
• the segments are not superelastic.
• the invention is directed to a medical guidewire having been formed at least in part of a shape-memory metal. Different portions of the shape-memory metal have been treated differently to have different shape-memory properties.
• the guidewire is subjected to a local heat treatment resulting in a reduced stiffness compared with the remainder of the guidewire.
• a guidewire of desired flexibility can be prepared.
• the invention is directed to implantable medical filters such as vena cava filter having been formed of shape-memory materials. At least a portion of the shape-memory material is differently treated to alter the shape- memory properties of the material relative to the untreated shape-memory material. Desirably, the differently treated portion will be heat treated and exhibit a greater tendency toward plastic deformation relative to the remainder of the filter.
• Figure 4a is a side elevational view of a stent made in accordance with the present invention.
• Figure 4b is a side elevational view of the stent of Fig. 4a after it has been bent.
• Figures 5 a and 5 b are views of embodiments of the invention in which connecting segments have been treated.
• Fig. 6a shows a side elevational view of an inventive guidewire.
• Fig. 6b shows the guidewire of Fig. 6a in a bent configuration.
• Fig. 6c shows the guidewire of Fig. 6b after it has been released from the bent configuration.
• Fig. 6d shows a side elevational view of an inventive guidewire whose distal tip has been treated to exhibit a reduced stiffness.
• Fig. 7a shows a side elevational view of a prior art guidewire.
• Fig. 7b shows the guidewire of Fig. 7a in a bent configuration.
• Fig. 8 shows a side elevational view of an inventive vena cava filter.
• the present invention is directed to the selective treatment of portions of a medical device containing a shape memory material. More specifically, the invention is directed to differential treatment of the shape memory material in a medical device to achieve different physical properties in different portions of the device.
• Medical devices made of a shape memory material such as Nitinol typically have shape memory characteristics. The shape memory characteristics of the material may be altered by heat treating the material.
• By locally treating portions of a shape-memory metal it is possible to produce a metal with spatial variations in the elasticity and stiffness of the metal. The locally treated portions will initiate plastic deformation at a lower strain than the portions that have not been locally treated.
• the material may simply have a reduced stiffness in the locally treated portion or the superelasticity of the locally treated portion may be destroyed with the locally treated portion being plastically deformable.
• a stress-strain curve (solid line) is shown for a shape-memory material.
• the stress-strain curve (dashed line) for the same material following additional heat treatment of the material is also shown.
• the material has a reduced load and unload plateau, as shown in Fig. 1 and the material initiates plastic deformation at a lower strain level.
• the shape memory material based medical device is typically subject to a first annealing using standard annealing processing conditions as are known in the art. Desirably, the device will be annealed for about 5 minutes to about 40 minutes at a temperature ranging from about 400 C to about 575 C. More desirably, the device will be annealed for about 10 minutes to about 15 minutes. Also more desirably, the device will be annealed at a temperature ranging from about 450 C to about 550 C. Shorter or longer periods may be used as may higher or lower temperatures, depending on the material being annealed and the desired properties of the material.
• Another suitable method involves applying a heated inert gas jet to a desired portion of the medical device to selectively heat a desired portion of the device.
• Yet another method involves the use of an induction coil.
• An induction coil may be placed over a desired portion of the medical device to effect induction heating of the desired portion of the medical device.
• a laser may also be used to selectively heat desired regions of the medical device.
• the desired regions of the medical device may -7- also be brazed.
• the medical device may also be placed in a heat treating fluid such as a salt bath or a fluidized sand bath with appropriate sections of the device insulated.
• the second annealing step is typically carried out at a temperature of about 550 C to about 600 C for about five minutes to about 20 minutes. At such temperatures, the stiffness of the material will be reduced. As with the first annealing step, the exact time and temperature of the second annealing step depends on the material chosen (i.e. its composition) and on the form of the material (for example, in wire form or in sheet form). In certain cases, it may be desirable for the second annealing step to be carried out over shorter or longer periods of time and at lower or higher temperatures than those disclosed above.
• the invention contemplates localized heat treating of a variety of medical devices including stents, medical guidewires and filters such as vena cava filters.
• stents include a variety of related devices including stents, grafts and stent-grafts in particular and endoluminal prostheses in general.
• the invention is directed to a stent, shown generally at 100, comprised of a plurality of cells 104 arranged in columns 108 extending from one end 112 of the stent to the other end 116. Adjacent columns 108 of cells 104 are interconnected.
• the stent includes at least one differently treated column 108a of cells 104a which has been treated differently from the remainder of columns 108b to have different shape-memory properties from the remainder of the stent.
• differently treated column 108a will be characterized by an increased tendency to plastic deformation relative to the remainder of the stent and will be plastically deformable. More desirably, the superelasticity of the differently treated portion will be destroyed as a result of the heat treatment.
• the invention also contemplates treating the column(s) such that the treated portion loses its shape memory characteristic.
• Fig. 3b shows the stent of Fig. 3a in a partially expanded state.
• Untreated columns 108b are shown in an expanded state, having been exposed to a sufficient temperature to cause the metal to transition to its austenitic state.
• Treated column 108a is in an unexpanded state, the superelastic properties of the material having been locally destroyed.
• the stent may later be 'touched up' via mechanical expansion of the cells of the treated column to better fit in a lumen.
• the invention is also directed to the stent shown generally at 100 in Fig. 5a, comprised of a plurality of spaced segments 120.
• Each segment 120 is desirably comprised of a series of interconnected cells 124.
• cells 124 will be of polygonal configuration in plan view. More desirably, they will be hexagonal.
• Adjacent spaced segments 120 are connected to each other by one or more connector sections 128.
• Connector sections 128 may be disposed at an oblique angle relative to the longitudinal axis 180 of the stent as shown in Fig. 5a or they may be substantially parallel to the longitudinal axis 180 as shown in Fig. 5b. They may be straight or curved.
• Segments 120 have been subjected to a local heat treatment, in accordance with the invention. Desirably, segments 120 will be of lower stiffness than connector sections 128 as a result of the heat treatment.
• Stent 100 may be made of any suitable shape-memory material including shape-memory metals such as Nitinol. Nitinol with a composition of about 55.75% (by weight) nickel and 44.25% (by weight) titanium may be particularly well suited for use in the present invention.
• the stent may be made of shape-memory wire or a sheet or tube of shape-memory material.
• the invention is also directed to stents similar to those shown in Figs. 5a and 5b, such as those disclosed in US 08/942162 incorporated herein in its entirety by reference, wherein the connector sections and the segments are subject to different heat treatments.
• stent configurations of Figs. 3-5 are intended to be exemplary. Stents with other designs may be treated similarly.
• the invention is directed to medical guide wires made of shape-memory materials, portions of which have been differentially treated.
• a medical guidewire such as that shown at 200 in Fig. 6a, is specially treated toward distal end 204 of the guidewire.
• Region 208 of the device is heat treated to increase the tendency toward plastic deformation of the treated portion relative to the remainder of the guidewire. This, in turn, allows the guidewire to have a region of greater flexibility and a region of reduced flexibility corresponding to the locally treated section of the guidewire.
• Figs. 6b and Fig. 6c illustrate the guidewire of Fig. 6a as it is bent and released.
• guidewire 200 is bent.
• Region 208 has a greater tendency toward plastic deformation.
• the remainder 212 of guidewire 200 is in the austenitic state and thus deforms elastically.
• the guidewire of Fig. 6b is shown in Fig. 6c after it has been released from its bent position.
• Locally treated region 208 remains bent while austenitic regions 212 recovery fully to their configuration prior to being bent.
• Nitinol which has been treated to have spatially varying properties, it is possible to prepare a guidewire which may be permanently deformed within the body.
• a local heat treatment may also be used to reduce the stiffness of the tip of the guidewire prior to inserting the guidewire into the body. This is illustrated schematically in Fig. 6d. Distal end 204 of guidewire 200 has been subject to an additional heat treatment to reduce the stiffness of the distal end relative to the remainder of the guidewire. If the superelasticity is completely destroyed, a permanent bend may be placed in the guidewire, thereby allowing a physician to shape a guide wire as desired.
• a fully austenitic guidewire is shown in various states in Figs. 7a-c.
• Fig. 7a shows guidewire 200.
• the entire guidewire is in the austenitic state 212.
• guidewire 200 is shown in a bent configuration.
• a small region 208 is in a stress-induced martensitic state while the remainder 212 of guidewire 200 is in the austenitic phase.
• the entire guidewire Upon release of the guidewire, as shown in Fig. 7c, the entire guidewire returns to the configuration it had prior to being bent.
• the entire guidewire is in the austenitic state.
• the invention is directed to medical filters made, at least in part, of differentially treated shape-memory materials.
• Fig. 8 shows a vena cava filter generally at 300.
• Vena cava filter 300 is similar in design to that disclosed in commonly assigned US Patent 5,709,704 to Nott et al., the content of which is incorporated herein in its entirety by reference.
• Filter 300 is constructed, at least in part, of a shape memory material.
• Filter 300 includes a single cell 304 in which the shape-memory material is differentially heat treated to increase the tendency to plastic deformation of the desired portion of the filter.
• binary shape-memory metals such as Nitinol or other alloys of Nickel and Titanium will be used.
• the invention also contemplates the use of doped binary metals as well. Suitable dopants include Chromium, Niobium and Vanadium. Additional suitable shape-memory alloys are disclosed in WO 95/31945, the contents of which are incorporated herein in their entirety by reference.

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